Purpose:
Reading performance is an important tool to evaluate patients with impaired vision. Reading speed, reading acuity and critical print size are factors that mainly influence reading performance in normal and low-vision subjects. The aim of this study was to investigate the impact of a recently developed low-cost electronic portable magnifier reading system (PRS) in the reading performance of low-vision subjects.

Methods:
Ten adult subjects (ages ranging from 20 to 92 years) with low vision and without any training for low vision devices were included. Reading performance was assessed binocularly with best optical correction with the Minnesota Reading Speed Chart version for the Portuguese language (MNREAD Portuguese). PRS apparatus is composed of a system of image capturing coupled with a 5.6 inch monochromatic monitor, providing up to 15 x standard magnification. Parameters of reading speed (words per minute), reading acuity (logMAR), and critical print size (logMAR) were determined without and with the PRS prototype. Paired t-test was used to compare results with and without PRS prototype for reading performance parameters. When normality test failed, Wilcoxon signed rank test was used. Statistical significance was set at p≤0.05.

Results:
Mean reading speed was 48.4 ± 30.5 words per minute without PRS, decreasing to 45.0 ± 19.6 words per minute with PRS utilization without any significance. All subjects showed improvement in both reading acuity and critical print size with PRS prototype. Mean reading acuity without PRS prototype (1.00 ± 0.23 logMAR) was statistically poorer (t=13.054, p≤0.001) than that measured with it (-0.08 logMAR ± 0.25). The same trend was found in mean critical print size, with 1.15 ± 0.18 logMAR without the PRS prototype and for values significantly better (t=16.694, p≤0.001) with prototype (0.13 ± 0.25 logMAR).

Conclusions:
Considerable improvement in both reading acuity and critical print size was provided by PRS prototype use. However, reading speed results had no statistical differences with and without PRS prototype in this small cohort of patients. Further studies with large numbers of patients are recommendable to corroborate and extend the findings with this new promising technology.